{ "id": "decaffeination", "url": "https://coffearium.org/entries/decaffeination/", "license": "CC-BY-4.0", "title": "Decaffeination", "summary": "How caffeine is taken out of green coffee before roasting – with organic solvents, water or carbon dioxide – what else leaves the bean, what the law calls decaffeinated, and how decaf roasts differently.", "domain": "roasting", "kind": "Process", "stage": "roast", "topics": [ "science", "history" ], "topicSections": {}, "lang": "en", "status": "verified", "reviewer": "Coffearium verification pass", "lastVerified": "2026-10-14T00:00:00.000Z", "updated": "2026-10-14T00:00:00.000Z", "added": "2026-10-14T00:00:00.000Z", "brief": [ "Decaffeination happens on green coffee, before roasting. Every industrial process moistens the beans, extracts the caffeine and dries the beans again.1", "Three solvent families are used – organic solvents (dichloromethane, ethyl acetate), water, and carbon dioxide (supercritical or liquid).1", "Decaf is not caffeine-free. The US Food and Drug Administration (FDA) gives 2–15 mg per 8 fl oz cup (about 240 mL) as typical.13", "The EU limits dichloromethane residues to 2 mg/kg in roasted coffee; the US limit is 10 parts per million in decaffeinated roasted coffee.5,7", "Other compounds leave with the caffeine. In one industrial dichloromethane process, green arabica lost 60% of its sucrose.2" ], "quickFacts": [ { "label": "When", "value": "On green coffee, before roasting" }, { "label": "Common sequence", "value": "Moisten, extract caffeine, dry" }, { "label": "Solvents in industrial use", "value": "Dichloromethane, ethyl acetate, water, CO₂ (supercritical or liquid)" }, { "label": "Decaf beans, Germany", "value": "≤ 1 g caffeine per kg coffee dry matter" }, { "label": "Decaf extracts, EU", "value": "≤ 0.3% anhydrous caffeine in coffee-based dry matter" }, { "label": "Dichloromethane residue", "value": "EU ≤ 2 mg/kg roasted coffee; US ≤ 10 ppm" }, { "label": "Ethyl acetate", "value": "Good manufacturing practice, no numerical limit (EU, US)" }, { "label": "Decaf in the cup", "value": "Typically 2–15 mg per 8 fl oz, about 240 mL (FDA)" } ], "aka": [ "Decaf", "Decaffeinated coffee", "Decaffeinating" ], "linkTerms": [ "decaffeinated", "decaffeination process", "CO₂ decaffeination", "water process decaf", "solvent decaffeination", "ethyl acetate" ], "related": [ "caffeine", "caffeine-and-roast-degree", "roasting", "green-coffee-composition", "roast-degree-and-colour", "roast-loss", "fluid-bed-roaster", "maillard-reaction", "acids-in-coffee", "freshness-and-storage" ], "contested": [ "Year Runge isolated caffeine: a German national biography dates the discovery to 181916; a textbook chapter gives 1820.1 Runge’s two-volume book on his phytochemical discoveries appeared in 1820/21.16 No source opened for this entry settles the date.", "Which process keeps the most aroma: no study opened for this entry compared all three method families on the same green coffee and the same roast. A 2023 study of commercial Brazilian coffees from one region found the water-processed decaf with the lowest total aroma intensity18; a textbook chapter notes that different green coffees normally go through different industrial processes, which makes fair comparisons rare.1" ], "corrections": [], "sources": [ { "id": "s1", "title": "Decaffeination – Process and Quality", "authors": "Pietsch, A.", "year": 2017, "publisher": "In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 10, pp. 225–243", "url": "https://doi.org/10.1016/B978-0-12-803520-7.00010-4", "doi": "10.1016/B978-0-12-803520-7.00010-4", "tier": "B", "quote": "In summary the process sequence in all industrial processes is bean prewetting with water, caffeine extraction, and subsequent bean drying.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s2", "title": "Efeito do processo de descafeinação com diclorometano sobre a composição química dos cafés arábica e robusta antes e após a torração", "authors": "Toci, A.; Farah, A.; Trugo, L. C.", "year": 2006, "publisher": "Química Nova 29(5), 965–971", "url": "https://www.sbq.org.br/39ra/quimicanova-sub/audiencia_pdf_asp-aid2-2492-nomeArquivo-Vol29No5_965_14-AR05334.pdf", "tier": "A", "quote": "A significant change in the chemical composition of both C. arabica and C. canephora species was observed, with differences between species and degrees of roasting.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s3", "title": "Supercritical carbon dioxide decaffeination process: a life cycle assessment study", "authors": "De Marco, I.; Riemma, S.; Iannone, R.", "year": 2017, "publisher": "Chemical Engineering Transactions 57, 1699–1704", "url": "https://www.aidic.it/cet/17/57/284.pdf", "doi": "10.3303/CET1757284", "tier": "A", "quote": "the extracting process goes on for 11.5 hours in the case of arabica and 22 hours in the case of robusta coffee", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s4", "title": "Appendix E – Critical Properties of Selected Fluids. In: Introduction to Engineering Thermodynamics", "authors": "Yan, C. Y.", "publisher": "University of British Columbia Okanagan, via BCcampus; LibreTexts Engineering", "url": "https://eng.libretexts.org/Bookshelves/Mechanical_Engineering/Introduction_to_Engineering_Thermodynamics_(Yan)/07%3A_Appendices/7.05%3A_Appendix_E_-_Critical_Properties_of_Selected_Fluids", "tier": "B", "quote": "Carbon Dioxide", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s5", "title": "Directive 2009/32/EC of the European Parliament and of the Council of 23 April 2009 on the approximation of the laws of the Member States on extraction solvents used in the production of foodstuffs and food ingredients (Recast)", "authors": "European Parliament; Council of the European Union", "year": 2009, "publisher": "Official Journal of the European Union, L 141, 6 June 2009, pp. 3–11 (EUR-Lex; current consolidated version 16 February 2023)", "url": "https://eur-lex.europa.eu/eli/dir/2009/32/oj", "tier": "A", "quote": "2 mg/kg in the roasted coffee and 5 mg/kg in the tea", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s6", "title": "Commission Directive (EU) 2023/175 of 26 January 2023 amending Directive 2009/32/EC of the European Parliament and of the Council as regards 2-methyloxolane", "authors": "European Commission", "year": 2023, "publisher": "EUR-Lex", "url": "https://eur-lex.europa.eu/eli/dir/2023/175/oj/eng", "tier": "A", "quote": "Commission Directive (EU) 2023/175 of 26 January 2023 amending Directive 2009/32/EC", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s7", "title": "21 CFR 173.255 – Methylene chloride", "authors": "U.S. Food and Drug Administration", "year": 2026, "publisher": "Electronic Code of Federal Regulations (eCFR), Title 21, up to date as of 8 October 2026", "url": "https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-173/subpart-C/section-173.255", "tier": "A", "quote": "In coffee as a residue from its use as a solvent in the extraction of caffeine from green coffee beans, at a level not to exceed 10 parts per million (0.001 percent) in decaffeinated roasted coffee and in decaffeinated soluble coffee extract (instant coffee).", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s8", "title": "21 CFR 173.228 – Ethyl acetate", "authors": "U.S. Food and Drug Administration", "year": 2026, "publisher": "Code of Federal Regulations, Title 21; text at Legal Information Institute, Cornell Law School", "url": "https://www.law.cornell.edu/cfr/text/21/173.228", "tier": "A", "quote": "as a solvent in the decaffeination of coffee and tea.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s9", "title": "Food Additive Petition From Environmental Defense Fund, et al.; Request To Amend the Food Additive Regulations To Remove the Solvents Benzene, Ethylene Dichloride, Methylene Chloride, and Trichloroethylene; Reopening of the Comment Period (Docket No. FDA-2023-F-5684)", "authors": "U.S. Food and Drug Administration", "year": 2026, "publisher": "Federal Register 91, 31681–31682, 28 May 2026 (FR Doc. 2026-10615; GovInfo)", "url": "https://www.govinfo.gov/content/pkg/FR-2026-05-28/pdf/2026-10615.pdf", "tier": "A", "quote": "In the Federal Register of January 11, 2024 (89 FR 1857), FDA announced that we had filed a food additive petition", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s10", "title": "Directive 1999/4/EC of the European Parliament and of the Council of 22 February 1999 relating to coffee extracts and chicory extracts (consolidated version of 18 November 2013)", "authors": "European Parliament; Council of the European Union", "year": 1999, "publisher": "EUR-Lex", "url": "https://eur-lex.europa.eu/eli/dir/1999/4/2013-11-18", "tier": "A", "quote": "the labelling must include the term ‘decaffeinated’ in the case of the products defined in point 1 of the Annex, provided that the anhydrous caffeine content does not exceed 0,3 % by weight of the coffee-based dry matter.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s11", "title": "Verordnung über Kaffee, Kaffee- und Zichorien-Extrakte (Kaffeeverordnung, KaffeeV) vom 15. November 2001", "authors": "Federal Republic of Germany", "year": 2001, "publisher": "Bundesgesetzblatt I, p. 3107; official consolidated text at Gesetze im Internet (Bundesministerium der Justiz / Bundesamt für Justiz); § 2(3) no. 1(a) checked on 14 Oct 2026 in the FAOLEX copy of the text as amended on 22 February 2006", "url": "https://www.gesetze-im-internet.de/kaffeev_2001/BJNR310700001.html", "tier": "A", "quote": "Rohkaffee und Röstkaffee, der höchstens ein Gramm Koffein in einem Kilogramm Kaffeetrockenmasse,", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s12", "title": "Commercial Item Description: Coffee (A-A-20213B)", "authors": "U.S. Department of Agriculture, Agricultural Marketing Service", "year": 2004, "publisher": "U.S. Department of Agriculture, 17 August 2004", "url": "https://www.ams.usda.gov/sites/default/files/media/CID%20Coffee.pdf", "tier": "A", "quote": "Test results for caffeine shall be reported to the nearest 0.01 percent.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s13", "title": "Spilling the Beans: How Much Caffeine is Too Much?", "authors": "U.S. Food and Drug Administration", "year": 2024, "publisher": "U.S. Food and Drug Administration, Consumer Updates (content current as of 28 August 2024)", "url": "https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much", "tier": "A", "quote": "For example, decaf coffee typically has 2 to 15 milligrams in an 8-fluid-ounce cup.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s14", "title": "Treatment of coffee (US Patent 897,763)", "authors": "Meyer, J. F., Jr.; Roselius, L.; Wimmer, K.", "year": 1908, "publisher": "United States Patent Office; filed 4 May 1906, granted 1 September 1908", "url": "https://patents.google.com/patent/US897763A/en", "tier": "A/B", "tierNote": "A for its own inventors, dates and the process it describes; never for how well the process works.", "quote": "washed out with chloroform or benzene", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s15", "title": "Fremgangsmåde til fjernelse af koffein fra råkaffe (DK 131081 B; priority German application DE 2005293, filed 5 February 1970)", "authors": "Zosel, K.; Studiengesellschaft Kohle mbH", "year": 1975, "publisher": "Danish Patent Office; family record at Google Patents", "url": "https://patents.google.com/patent/DK131081B/GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html", "tier": "A/B", "tierNote": "A for its own inventor, applicant, numbers and dates; never for how well the process works.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s16", "title": "Runge, Friedlieb Ferdinand", "authors": "Priesner, C.", "year": 2005, "publisher": "Neue Deutsche Biographie 22, pp. 263–264 (Historische Kommission bei der Bayerischen Akademie der Wissenschaften)", "url": "https://www.deutsche-biographie.de/sfz77382.html", "tier": "A", "quote": "der ihm die Untersuchung von Kaffeebohnen empfahl, in denen R. 1819 das Coffein entdeckte.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s17", "title": "Distinguishing between Decaffeinated and Regular Coffee by HS-SPME-GC×GC-TOFMS, Chemometrics, and Machine Learning", "authors": "Zou, Y.; Gaida, M.; Franchina, F. A.; Stefanuto, P.-H.; Focant, J.-F.", "year": 2022, "publisher": "Molecules 27(6), 1806", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8948847", "doi": "10.3390/molecules27061806", "tier": "A", "quote": "Pyrazines were more enriched in the regular coffee, which was due to the reduction of sucrose during the decaffeination process.", "accessed": "2026-10-14T00:00:00.000Z" }, { "id": "s18", "title": "Changes in aroma compounds of decaffeinated coffee beans", "authors": "Lee, J.-Y.; Kim, Y.-S.", "year": 2023, "publisher": "Korean Journal of Food Preservation 30(3), 492–501", "url": "https://www.koreascience.or.kr/article/JAKO202307957700471.pdf", "doi": "10.11002/kjfp.2023.30.3.492", "tier": "A", "quote": "We identified 28 volatile aroma compounds from RC, SWDC, and SCDC", "accessed": "2026-10-14T00:00:00.000Z" } ], "markdown": "## What decaffeination is\n\nDecaffeination removes most of the caffeine from coffee. It is done on green coffee, before roasting. According to a textbook chapter, aroma forms mainly during roasting, which comes afterwards.1 A decaffeination plant therefore sits between the green coffee trade and the roaster. Several plants also steam green coffee or give it other treatments that do not aim to remove caffeine.1\n\nDecaf is not caffeine-free. The US Food and Drug Administration (FDA) says decaf coffee typically has 2–15 mg in an 8-fluid-ounce cup (about 240 mL).13 How much caffeine regular coffee holds, and what it does in the body, is covered in *Caffeine*.\n\n## Why the beans are moistened first\n\nEarly attempts to extract caffeine from dry beans with organic solvents failed, according to a textbook chapter.1 The working method came when the beans were first wetted and swollen with water and steam. The same chapter states that the added water frees caffeine from a structure it forms with chlorogenic acids.1\n\nWetting also opens the bean, so the solvent can reach the caffeine more easily.1 In one industrial carbon dioxide plant, steam raised the moisture of the beans to 30% by weight (basis not stated).3 After extraction, the water has to be dried out again – a costly step.1 So every industrial process follows the same three steps: moisten, extract, dry.1\n\n## Three families of methods\n\nAccording to a 2017 textbook chapter, four extraction solvents are in industrial use: dichloromethane, ethyl acetate, water and carbon dioxide.1 Carbon dioxide is used either as a supercritical fluid or as a liquid.1 In each case a solvent loop carries the caffeine away from the beans and is cleaned for reuse.1\n\n
\n
\n

A · Organic solvent

\n
    \n
  1. Moistened green coffee. Extracted in fixed beds or rotating drums.1
    2. \n
  2. Solvent with caffeine. Dichloromethane or ethyl acetate; both barely mix with water.1
    3. \n
  3. Still. Distillation recovers the solvent; caffeine is separated from the residue and refined.1
    4. \n
  4. Clean solvent back. Repeated extractions, or vessels in countercurrent, are needed. Steam then strips off the remaining solvent.1
    5. \n
\n

B · Water or green-coffee extract

\n
    \n
  1. Moistened green coffee. Hot water extracts caffeine but also sugars and other solubles.1
    2. \n
  2. Extract with caffeine. Fresh water, or water already loaded with the other green-coffee solubles.1
    3. \n
  3. Activated carbon. A selective carbon holds the caffeine; most other substances stay in the water.1
    4. \n
  4. Extract back to the beans. Either concentrated and added back to dried beans, or reused for the next extraction.1
    5. \n
\n

C · Carbon dioxide

\n
    \n
  1. Moistened green coffee in a high-pressure vessel. Supercritical or liquid carbon dioxide.1
    2. \n
  2. CO₂ with caffeine. Dissolves less caffeine than other solvents but is more selective.1
    3. \n
  3. Wash column or activated carbon. Water or carbon takes the caffeine out of the CO₂.1,3
    4. \n
  4. Clean CO₂ back. The purified CO₂ returns to a storage tank for reuse.3
    5. \n
\n
The three families of decaffeination process: in each, a solvent loop carries caffeine from moistened green coffee to a separator and returns. Schematic, not to scale.
\n
\n\n**Organic solvents.** Dichloromethane (also called methylene chloride) and ethyl acetate are the two in common use.1 A textbook chapter notes that dichloromethane is flame resistant but falls under strict emission and health-protection laws. Ethyl acetate is not chlorinated but is flammable.1\n\n**Water.** Hot water dissolves caffeine well, but it also takes sugars and other aroma precursors.1 The process either gives these back to the beans or prevents their loss by using water already saturated with them.1\n\n**Carbon dioxide.** Above about 31 °C and 7.4 MPa (74 bar), carbon dioxide becomes a supercritical fluid.1,4 It is readily available and non-flammable, but the plant needs costly high-pressure equipment.1\n\n## What the law calls decaf\n\nThere is no single worldwide definition of “decaffeinated”.1 In the EU, only coffee extracts (instant coffee) have one common rule; beans fall under national law.1,10\n\n| Jurisdiction | Product | Limit | Legal basis |\n|---|---|---|---|\n| European Union | Coffee extracts labelled “decaffeinated” | Anhydrous caffeine ≤ 0.3% of coffee-based dry matter | Directive 1999/4/EC10 |\n| Germany | Green and roasted coffee labelled “entkoffeiniert” | ≤ 1 g caffeine per kg coffee dry matter (0.1%) | KaffeeV11 |\n| United States | Decaffeinated coffee bought to the federal specification | Caffeine ≤ 0.10%, dry basis in the package | USDA Commercial Item Description A-A-20213B12 |\n| United States | Labelling of decaf coffee | No caffeine limit found in FDA regulations opened for this entry; FDA gives 2–15 mg per 8 fl oz cup as typical | FDA13 |\n| European Union | Dichloromethane residue | ≤ 2 mg/kg in roasted coffee | Directive 2009/32/EC5 |\n| European Union | Ethyl acetate, carbon dioxide | Good manufacturing practice, for all uses | Directive 2009/32/EC5 |\n| United States | Methylene chloride (dichloromethane) residue | ≤ 10 ppm in decaffeinated roasted coffee and decaffeinated instant coffee | 21 CFR 173.2557 |\n| United States | Ethyl acetate | Good manufacturing practice, as a solvent in decaffeinating coffee and tea | 21 CFR 173.2288 |\n\nThe US specification is a purchasing description for coffee bought by federal, state and local governments and other interested parties.12 No caffeine limit for labelling decaf was found in the FDA regulations opened for this entry. A percentage of caffeine “removed” is quoted for US decaf; according to a textbook chapter, it is a threshold derived from average caffeine contents, not a formal regulation.1\n\n## Roasting decaffeinated coffee\n\nDecaffeinated green coffee often looks dull, yellowish or even brownish rather than green, according to a textbook chapter.1 Some treated beans come close to the look of roasted beans, which makes control by eye harder.1 The same chapter says roasting must be adapted. The target colour may differ, and roast loss can be the better end-point.1\n\nIn a 2023 study, commercial decaffeinated beans from Cerrado, Minas Gerais, Brazil, were charged at 170 °C and roasted for 8 min; the regular beans were roasted for 10 min.18 The decaf beans still ended darker: Agtron 49.20 (water process) and 47.67 (CO₂), against 55.38 for the regular coffee.18 Decaffeinated beans are also more brittle. They need more care in fluid-bed roasters, and industrial roller mills need adapted gap settings.1\n\n\n\n## Organic solvents in detail\n\nAccording to a textbook chapter, the solvent must hardly mix with water, so that it takes caffeine but leaves the other water-soluble components in the moist bean.1 Diffusion of caffeine inside the bean is slow and controls the rate, so intense agitation is not needed. Its limited capacity calls for repeated extractions or countercurrent vessel sequences.1 Steam then strips the remaining solvent, and the beans are dried with air, often in a sequence of dryers; low air temperatures and the exclusion of oxygen help to limit aroma loss.1 The recovered caffeine is refined and sold to the pharmaceutical and beverage industries; the waxy remainder is used as a binder or fuel.1\n\n**Residue limits.** In the EU, dichloromethane may be used to decaffeinate coffee and tea, with a maximum residue of 2 mg/kg in roasted coffee.5 Ethyl acetate is on the EU list of extraction solvents allowed for all uses under good manufacturing practice, with carbon dioxide, ethanol and acetone among others.5 In the US, methylene chloride residues may not exceed 10 ppm (0.001%) in decaffeinated roasted coffee and decaffeinated instant coffee7; ethyl acetate may be used under current good manufacturing practice.8\n\n**Status as of October 2026.** The latest consolidated version of the EU directive dates from 16 February 2023; the amendment behind it concerns another solvent, 2-methyloxolane.6 No change to the dichloromethane entry for coffee was found in the EU sources opened for this entry. In the US, the FDA announced in January 2024 that it had filed a food additive petition from the Environmental Defense Fund and others. The petition asks the FDA to remove four solvents, methylene chloride among them, from its food additive regulations.9 In May 2026 the FDA reopened the comment period until 29 June 2026 (docket FDA-2023-F-5684).9 No FDA decision was found as of 14 October 2026; the eCFR text, up to date as of 8 October 2026, still sets the 10 ppm limit for decaffeinated coffee.7 How caffeine and decaf relate to health is covered in *Caffeine*.\n\n## Water processes in detail\n\nCaffeine dissolves much better in hot water than in cold, so extraction runs with hot water at atmospheric pressure.1 The difficulty is selectivity: sugars and other aroma precursors are extracted too.1 A textbook chapter describes two answers.1\n\n- **Fresh water and add-back.** The extract passes a bed of activated carbon chosen to hold caffeine. The nearly caffeine-free extract is concentrated and added back to the beans, which must first be partly dried to absorb it.1\n- **Preloaded water.** Water from earlier batches is free of caffeine but saturated with the other green-coffee solubles, so it takes little else from new beans. The caffeine is removed from it either by an organic solvent in liquid–liquid extraction or by an adsorbent.1 Carbons made more selective, or preloaded with sucrose or glucose to block sites that would otherwise take up similar coffee compounds, are used.1\n\n## Carbon dioxide in detail\n\nCarbon dioxide reaches its critical point at 304.1 K (about 31 °C) and 7.38 MPa.4 A textbook chapter states that supercritical decaffeination runs at about 25 MPa and 100 °C.1 A 2017 life cycle assessment of one industrial plant describes these steps:3\n\n1. Steaming at 90 °C for 5 h, until the beans hold 30% moisture by weight.3\n2. Extraction at 90 °C and 250 bar: 11.5 h for arabica and 22 h for robusta.3\n3. Countercurrent washing of the CO₂ with water, which removes 99.5% of the caffeine from the gas; the purified CO₂ returns to storage.3\n\nAccording to the same chapter, wet CO₂ dissolves more caffeine than dry CO₂, and its solubility falls sharply when the caffeine must leave a water phase full of coffee solubles.1 Liquid CO₂ works at lower temperature, which reduces thermal stress, but needs longer processing because caffeine is much less soluble in it.1 The use of supercritical carbon dioxide to decaffeinate green coffee goes back to a patent by Zosel (see History).1,15\n\n## What else leaves the bean\n\nNo decaffeination process removes caffeine alone. A 2006 study analysed arabica and robusta before and after industrial decaffeination with dichloromethane, by direct extraction of the green coffee.2 Caffeine fell from 0.98 to 0.02 g/100 g (dry basis) in arabica and from 2.15 to 0.07 g/100 g in robusta2 – by our calculation, 98% and 96.7% of the caffeine removed. At the same time the green coffee lost about 60% of its sucrose (arabica) and 20% (robusta), and 16% and 11% of its chlorogenic acids.2 Trigonelline fell by 13% in arabica but rose by 27% in robusta; lipids and total carbohydrates changed less.2\n\n
\n
\n
Share of each compound lost from green coffee in one industrial dichloromethane decaffeination, arabica and robusta. Caffeine shares calculated from the reported contents before and after; the other values as reported.2
\n
\n\nAccording to a textbook chapter, sugars are aroma precursors.1 In a 2022 study of eight commercial pairs of regular and decaffeinated coffees, pyrazines were more abundant in the regular coffees; the authors attribute this to the loss of sucrose in decaffeination.17 According to a textbook chapter, mass is lost too, but reliable mass-loss data are rarely recorded and, as of 2017, no comparison between processes had been published.1 The same chapter states that treated beans generally keep for a shorter time than regular beans.1\n\n## Aroma and flavour\n\nThe two aroma studies opened for this entry agree that decaffeination shifts the volatile profile.17,18\n\n- **Eight commercial pairs (2022).** Headspace analysis of the ground coffees by two-dimensional gas chromatography separated regular from decaf coffees, using 20 discriminating features. Pyrazines were more abundant in regular coffee, and furan-derived compounds marked decaf.17\n- **Brazilian coffees from one region, two processes (2023).** Regular beans were compared with commercial beans from the same region decaffeinated by a water process and by supercritical CO₂. An electronic nose separated the CO₂ decaf from the regular coffee.18 The water-processed decaf had the lowest total aroma intensity, which the authors link to the loss of other soluble and aroma components.18 The roasts differed in time and colour, so the comparison does not separate decaffeination from roasting.18\n\nNo study opened for this entry ran a trained sensory panel on decaf made by different processes from one green coffee and roasted to the same colour.\n\n## History\n\nFriedlieb Ferdinand Runge discovered caffeine in coffee beans after Johann Wolfgang von Goethe suggested he examine them; a German national biography dates this to 181916, a textbook chapter to 1820.1 Both dates are listed under Contested.\n\nLudwig Roselius, founder of the German company Kaffee HAG, added the step that made decaffeination work: wetting and swelling the beans first, according to a textbook chapter.1 Johann Friedrich Meyer Jr., Roselius and Karl Wimmer of Bremen filed the US patent “Treatment of coffee” on 4 May 1906; it was granted on 1 September 1908 as US 897,763.14 In the patent, unbroken green beans are extracted under vacuum (with water in its worked example). The caffeine is washed out of the extract with chloroform or benzene, the rest of the extract is returned to the beans, and the beans are dried under vacuum.14 The patent text does not describe a separate steaming step.14\n\nZosel’s patent for decaffeinating green coffee with supercritical carbon dioxide goes back to a German application filed on 5 February 1970 (DE 2005293) by Studiengesellschaft Kohle.1,15 A textbook chapter dates the patent to 1971, the year of the foreign filings.1,15 According to a textbook chapter, patenting in decaffeination was intense in the 1980s and early 1990s and had nearly stopped by 2017; process details were then still often kept in-house.1\n\n## Reference values\n\nValues as reported in the sources. They describe single plants or studies, not targets.\n\n| Parameter | Value reported | Source |\n|---|---|---|\n| Moisture after steaming, one CO₂ plant | 30% by weight (basis not stated) | De Marco et al.3 |\n| Steaming, one CO₂ plant | 90 °C, 5 h | De Marco et al.3 |\n| Critical point of CO₂ | 304.1 K (about 31 °C), 7.38 MPa | Yan4; Pietsch1 |\n| Supercritical CO₂ extraction | 90 °C, 250 bar (one plant); about 100 °C and 25 MPa (textbook) | De Marco et al.3; Pietsch1 |\n| Supercritical CO₂ extraction time, one plant | 11.5 h (arabica); 22 h (robusta) | De Marco et al.3 |\n| Caffeine removed from CO₂ in the wash column | 99.5% | De Marco et al.3 |\n| Caffeine, green arabica before → after DCM decaffeination | 0.98 → 0.02 g/100 g (dry basis) | Toci et al.2 |\n| Caffeine, green robusta before → after DCM decaffeination | 2.15 → 0.07 g/100 g (dry basis) | Toci et al.2 |\n| Sucrose lost, green coffee | ≈ 60% (arabica); ≈ 20% (robusta) | Toci et al.2 |\n| Chlorogenic acids lost, green coffee | ≈ 16% (arabica); ≈ 11% (robusta) | Toci et al.2 |\n| Trigonelline change, green coffee | ≈ −13% (arabica); ≈ +27% (robusta) | Toci et al.2 |\n| Decaf roast, one study | Charge 170 °C; 8 min (decaf) vs 10 min (regular); Agtron 49.20 and 47.67 vs 55.38 | Lee & Kim18 |\n| Decaf in the cup, US | Typically 2–15 mg per 8 fl oz (≈ 240 mL) | FDA13 |\n\n## Open questions\n\n- **Process comparison on one coffee.** According to a textbook chapter, different green coffees normally go through different industrial processes, so fair flavour comparisons are rare.1 No study opened for this entry compared all three families on the same green coffee roasted to the same colour.\n- **Mass loss.** Reliable data on how much mass each process removes besides caffeine are rarely recorded.1\n- **Roasting decaf.** The statement that roast loss is sometimes the better control parameter than colour comes from a textbook chapter1; no study opened for this entry tested it.\n- **Dichloromethane in the US.** The reopened comment period on the food additive petition closed on 29 June 2026; no decision was found as of 14 October 2026.9\n\n## Key studies\n\n
\n

Toci, Farah & Trugo, 2006 – Dichloromethane decaffeination and green-coffee composition. Analysed arabica and robusta before and after industrial decaffeination with dichloromethane, green and roasted. Caffeine dropped to a few hundredths of a percent (dry basis). Sucrose, protein and trigonelline contents changed markedly, chlorogenic acids changed too, and lipids and total carbohydrates changed less.

\n

Química Nova 29(5), 965–971 · full text (PDF)

\n
\n\n
\n

Zou et al., 2022 – Telling decaf from regular by its volatiles. Compared the headspace of eight commercial pairs of regular and decaffeinated ground coffees by comprehensive two-dimensional gas chromatography and machine learning. Pyrazines marked regular coffee and furan-derived compounds marked decaf; the authors link the pyrazine gap to sucrose lost in decaffeination.

\n

Molecules 27(6), 1806 · doi:10.3390/molecules27061806

\n
\n\n
\n

Lee & Kim, 2023 – Aroma of water-processed and CO₂ decaf. Compared regular Brazilian beans with commercial beans from the same region decaffeinated by a water process and by supercritical CO₂. The decaf beans roasted darker in less time, and the water-processed decaf had the lowest total aroma intensity.

\n

Korean Journal of Food Preservation 30(3), 492–501 · doi:10.11002/kjfp.2023.30.3.492

\n
\n\n
\n

De Marco, Riemma & Iannone, 2017 – Life cycle of supercritical CO₂ decaffeination. A gate-to-gate life cycle assessment of an industrial supercritical CO₂ plant, per kilogram of decaffeinated coffee. It records the operating steps – steaming, extraction at 250 bar, water washing of the CO₂ – and their energy and material inputs.

\n

Chemical Engineering Transactions 57, 1699–1704 · doi:10.3303/CET1757284

\n
" }